CNC Plasma Cutter User Guide

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Shop Area: Metal Shop

Tool: CNC Plasma Cutter

Requires in-person training: Yes 

Procedure Number

UG 130-05, Rev. 2

Date

7/2/2026

 

GENERAL

Dynatorch CNC Plasma

The CNC Plasma cutter is used to cut 2D computer generated drawings from sheet and plate metals.

We have a Dynatorch XLS 5x10' CNC table powered by a Cutmaster 80 amp plasma cutter.

SAFETY

  • The plasma cutter requires at least shade #5 eye protection. Welding helmets can also be used.
  • PPE: remove tie, rings, watches and other jewelry, and roll sleeves up past the elbows. Remove all loose clothing and confine long hair. Wear close toed shoes.
  • Avoid standing in the travel path of the gantry.
  • Never cut or weld material with zinc in it, especially galvanized material, as it gives off toxic fumes.

REFERENCE

PROCEDURE

The general workflow for using the CNC plasma is as follows.

  1. CAD Design
  2. CAM toolpath creation
  3. Machine Setup and Control

There are many different software options that can be used to make it through this workflow; however the workflow taught at Vector Space is Inkscape/FreeCAD -> SheetCAM -> Dynatorch.

1. CAD

To create 2D drawings, Inkscape is recommended for artistic, freeform designs, while FreeCAD is recommended for technical drawings with precise dimensions. Both applications are available on all machines in the computer lab. Designs are typically saved in .dxf or .svg file format.

2. CAM

The purpose of the CAM process is to provide the tool with instructions on how to follow the CAD drawing. In the case of the plasma cutter, this typically means how to follow the lines, and at what speed. The software we recommend for this step is called SheetCAM and can be found on all machines in the computer lab. The input to the CAM software is a drawing (.dxf or .svg) and the output is gcode (.ngc).

SheetCAM

The step-by-step instructions below assume that you have already created your drawing in Inkscape or FreeCAD and are ready to import it into SheetCAM to prepare the code for cutting with the plasma cutter.

Set post-processor

SheetCAM is made to generate many different dialects of gcode, so it's important to set its output to the correct dialect for our machine.

  • Options -> Machine -> Post processor drop down to "Dynatorch plasma"

Import your drawing

  • To begin a new project, Click the File menu – New Part.  If you want to import a previously designed object from another program (dxf, svg, etc.), in the pop-up menu that opens, choose Yes when it asks if you want to Import a drawing, and then select your file from the explorer menu.
  • Under the drawing options, pay special attention to Scaling and Position
    • Scaling: This should usually be set to "1".
    • Position: Default is set to the bottom left corner.  This setting or any of the other corners would work best depending on if you have a blank piece of material.  If you set the position to center, the plasma cutter will always start from the bottom left corner of your material and move to the object.  If you are working around previous cuts, this makes the job much more difficult to position on the plasma cutter.
  • If you did not import a drawing file, you can create your object using the SheetCAM controls.

Creating and assigning layers

Once you have completed your design or finished adjusting settings for the imported object, you can create different layers for objects if you want them cut in a certain order.  For example, you may want the plasma cutter to cut the holes out first, then cut the rest of the design afterwards.  To do this the program has the ability to assign objects to different layers.

When choosing to create your layers, be sure to choose them in the order that you want them to be cut.  For example, choose the “Holes” layer first, and the rest of the design second.  Think about how each layer will affect the rest of the project.  Cutting the design first will probably drop it out of the material, so then it would be difficult to cut the holes after this happens.

  • The program will assign all objects to one layer initially.
  • To assign objects to a new layer, click the Mode menu and select Edit Contours.
  • Left click and hold, then drag the mouse over one or more objects and then release the button.  
  • Right click on any of the selected objects.  In the pop-up menu click Move to Layer, New layer (you will name it) or choose an existing layer to assign the object to a previously created layer.
  • To edit the options for each layer:
    • Click the Operation menu, Plasma Cut
    • Pay attention to the following options in the pop-up menu:
      • Contour method: Do you want the cutting to happen on the inside, outside, or middle of the path lines.  For example, you may want the holes to be cut on the inside, but the rest of the design on the outside.
      • Layer: Make sure you have selected the correct layer for the parameters you are setting.
      • Feed rate: The default for this is set to inches per minute (ipm), so if you wanted 20 mm/s, 40 ipm would be close to the same speed (47 ipm would be the exact same).
  • Click “OK”.  The path setting will now show up under “Operations” on the left sidebar off the program.  You can double click to edit them later if necessary.
  • When you have finished editing your object and adjusting settings for the layers, you can process the object to be run on the plasma cutter.

Processing your object

Once you have imported your object and adjusted the layers, it is time to process the image and create the code that will tell the plasma cutter how to cut the object.  The code you create here will be imported into the Mach3 program installed on the plasma cutter computer.

  • Click the File menu, choose Run post processor
  • Name your file and save as a G-code file (.ngc)

3. Machine Setup and Control

Dynatorch

  1. Fill water table using the fill switch. Stop the fill once the water level is at the top of the red metal bars, about 1 inch from overflowing the table. The water can overflow the table if you allow it.
  2. Launch Dynatorch software. Software will search for motors, it should find two X motors, one Y, and one torch motor.
  3. Allow homing process to establish a home position.
  4. Manually jog the torch to the X-Y origin of your job. Jog buttons are found in the upper right area.
  5. Set the origin by click X-zero and Y-zero in the upper left
  6. Run a test cut
    1. Disable the torch by clicking the lightning bolt
    2. Click Cycle Start to start the job
  7. Make any adjustments, then enable the torch and restart the job.
  8. When finished, open drain valve to empty water table. Once drained, close the drain valve using the switch.
  9. Remove workpiece from table.

Speed and Power

Reliable cut settings for the Dynatorch can be found here.

TUTORIAL

The tutorials below serve as reinforcement of content learned during an instructor-led workshop.

My First Plasma Cut

Your first plasma cut begins at the end of the typical workflow. The focus here is to understand the machine itself: how to setup and operate the plasma cutter.

  1. Download my_first_plasma_cut.ngc by right clicking the link and selecting Save Link As.
  2. Release the E-stop on the gantry.
  3. Begin filling the water table using the switch below the plasma cutter to turn on the pump.
  4. Launch the Dynatorch application.
  5. Allow the machine to home, and ensure that nothing stands in the way of the gantry and torch heading toward you.
  6. After the machine is homed, set your workpiece on the plasma table. Your workpiece needs to be a 16GA sheet of plain carbon steel for these instructions to be accurate.
  7. Set the speed and arc voltage parameters by clicking Cut Chart button at the center left of the screen. Then use the dropdowns to select Carbon Steel, 40 Amp. Then click Apply and you'll see these settings applied to the setpoints at the top of the screen.
  8. Ensure that the nozzle inside of the torch is rated for 40 Amps by unscrewing the grey part of the torch and separating the components until finding the engraving on the nozzle. If it is not correct, replace it with a 40 Amp nozzle. Re-assemble the torch and screw this assembly back onto the machine tight enough that the plasma cutter recognizes the re-installation and makes an audible click, but not so tight as to rotate the torch and damage the wires. Do NOT use a wrench or any tool other than your hand for this process.
  9. Using the control interface at the top right of the Dynatorch software, drive the torch to the bottom left corner of the workpiece.
  10. Zero the X and Y axes by clicking the associated buttons at the top left of the screen.
  11. Once the water table is filled, turn off the water pump.
  12. Turn on the plasma cutting power source (big box to the right of the computer). Turn the dial to 40 Amps.
  13. Prepare the software for a practice run by disabling the plasma arc. This is done by clicking the lightning bolt at the top center of the screen so that it becomes grey. Now click the start button at the center right of the screen. This will start the plasma torch moving without actually cutting. Observe the movement to ensure that it matches your expectations.
  14. Once happy with the practice run, click stop. This disables the X and Y motors, so re-enable those motors by clicking All Motors On at the top left of the screen. Then ensure that the gcode is reset to the very beginning by clicking the Reset button at the center right of the screen.
  15. Put on your safety glasses. Enable the plasma by clicking the lightning bolt. Then begin the operation by clicking Start.
  16. Drain the water table and cleanup your work.

My Second Plasma Cut

SheetCAM Simulation

Your second plasma cut begins a step further from the end, the focus of which is to understand how to generate gcode.

  1. Download my_second_plasma_cut.job.
  2. Launch the SheetCAM application from a desktop in the computer lab.
  3. Open my_second_plasma_cut.job by click File->Open Job.
  4. Ensure that your machine options are correct by clicking Settings->Machine Options. Click the PostProcessor tab and ensure that Dynatorch is selected as the postprocessor.
  5. The toolpaths have already been set in this file, but you should still review them to ensure that they make sense and to set your expectations for what will happen when the gcode is executed at the plasma cutter.
    1. Double click each of the two operations listed at the bottom left of the screen.
    2. Note the speed set for each operation, the layer that the operation is applied to, the lead-in and lead-out methods, and the offset selected.
  6. Now simulate the gcode by clicking Simulate, an aqua colored drill bit icon at the top center of the icon list.
  7. Generate the gcode by clicking File-> Run Post Processor.
  8. Once the gcode is ready, you are ready to repeat the process you learned in your first plasma cut.

My Third Plasma Cut

SheetCAM Toolpath Creation

Now we'll take another step back and create your own toolpaths.

  1. Download my_third_plasma_cut.svg.
  2. Launch the SheetCAM application from a desktop in the computer lab.
  3. Import the SVG file by File -> Import Drawing. Ensure that the file type filter at the bottom right has SVG files selected.
    1. Set drawing position to bottom left.
    2. Set scaling to 1.
    3. Click OK
  4. Create a plasma cutting tool by clicking Tools -> New Jet Cutting Tool.
    1. Name it plasma.
    2. Select Plasma from the Type dropdown list.
    3. Set the feedrate to 90 ipm.
    4. Leave the remaining fields at their defaults and click OK.
  5. Create a plasma cutting operation by clicking Operation -> Plasma Cut.
    1. Set Contour method to No Offset.
    2. Set Layer to black.
    3. Set Feedrate to 90 ipm.
    4. Set Lead in and Lead out to Arc with Length of 0.1 inch.
    5. Click OK.
  6. Repeat this process for the red layer, changing the Contour method to an Outside Offset.
  7. Save your work as a SheetCAM job file. File-> Save Job As.
  8. Continue with what you learned in from your Second Plasma Cut.

My Fourth Plasma Cut

If we were to take another step back, I'm afraid we'd step into an infinite number of tutorials, for after the creation of a drawing, we'd need to branch off into the fundamentals of art and computer science, which will ultimately take us all the way back to Euclid's Geometry. And while we encourage you to take these steps, we must end our tutorials here.

TROUBLESHOOTING

  • Torch is diving into the material after the arc initiates
    • Disable automatic torch height control

 

 

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